Date: Fri, 6 Mar 2009 16:17:15 +0100
From: martin f krafft <madduck@debian.org>
To: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: Future of md multipath
Message-ID: <20090306151715.GD6030@lapse.rw.madduck.net>
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also sprach Neil Brown <neilb@suse.de> [2009.03.06.0632 +0100]:
> > I understand that dm-multipath is more favourable, but unless
> > there's a riskless way to convert mdadm multipath into dm-multipath
> > on old systems, I don't think we have the option of deprecating it,
> > unless deprecation lasts for several years.
>=20
> Always the practical one, aren't you :-)

Goes with the territory. Debian does not need to make long term
support guarantees. They're inherent in our quality assurance,
security support, and chaotic organisation. :)

> I wonder how hard it would be to get mdadm to assemble a multipath
> using the 'dm' code rather than the 'md' code....
> Or to get the md layer in the kernel to hook in to the dm multipath
> implementation.

A migration isn't possible?

> I think it is probably worth putting in a printk now to say "You
> should probably be using dm-multipath".  But we probably do need
> to leave the code there for a while longer..

Maybe it would be possible to disable creation of new multipath
arrays, but still to support existing ones, insert the warning, and
quote a fixed deprecation date, say, 5 years into the future?

--=20
 .''`.   martin f. krafft <madduck@d.o>      Related projects:
: :'  :  proud Debian developer               http://debiansystem.info
`. `'`   http://people.debian.org/~madduck    http://vcs-pkg.org
  `-  Debian - when you have better things to do than fixing systems
=20
god is dead.
    -- nietzsche
nietzsche is dead.
    -- god
nietzsche is god.
    -- dead

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